Climatic and Human Influences on Groundwater in Low Atolls

Population centers in low, small islands have water supply problems that are among the most critical in the world. Limited land areas and extremely large soil hydraulic conductivities severely reduce surface runoff and surface storage, so that thin lenses of fresh groundwater floating over seawater comprise the major source of fresh water for people in many atolls. Atoll groundwater is extremely vulnerable to frequent El Niño Southern Oscillation (ENSO)-related droughts, salinization due to storm surges and sea-level rise, and to human activities with vadose zone transit times from surface to shallow groundwater being less than 1 h. We examine the relationship between groundwater, rainfall, and ENSO events in a low atoll, Tarawa, in the central and western Pacific Republic of Kiribati. Droughts can last as long as 43 months and occur with a current frequency of 6 to 7 years. The impact of droughts on the quality and quantity of a fresh groundwater lens is explored. The local drawdown of the water table due to pumping from long horizontal infiltration galleries is found to be less than diurnal tidal variations. The saturated hydraulic conductivity, K0, of the Holocene unconsolidated coral sands was estimated from infiltration gallery drawdown in two islands. The geometric mean K0 was 14.6 m d?1 with a range from 0.9 to 111 m d?1. These large K0 values cause the rapid transmission of rainfall and surface pollutants through the unsaturated zone to groundwater. An example is given of Escherichia coli pollution due to traditional activities. Strategies for improving the adaptation of island communities and increasing resilience to climate change are discussed

Safe water for people in low, small Island Pacific Nations: The rural-urban dilemma

The issue of ensuring that growing communities in small island countries have access to safe water and adequate sanitation is examined in Kiribati, whose islands are spread over three million square kilometres in the central Pacific. Its coral island communities have water supply and sanitation problems among the most difficult in the world. Formulaic developed-world approaches, models, techniques and toolboxes that do not consider the social and cultural context have had little success. Changes in approach at the international, national and local levels are called for, and the resourcing of village-level water and sanitation committees would return ownership and control in rural communities to its traditional base

Climatic and human influences on water resources in low atolls

Low, small islands have water supply problems amongst the most critical in the world. Fresh groundwater, the major source of water in many atolls, is vulnerable to natural and human-induced changes. Storm surges, droughts and over-extraction cause seawater intrusion. Settlements and agricultural activities can rapidly pollute shallow groundwaters. Limited land areas restrict freshwater quantities, which are especially vulnerable during frequent ENSO-related droughts. Demand for freshwater is increasing due to population growth and urbanisation. Water use for traditional crops often competes with water supplies for communities. This paper analyses the impact of frequent severe droughts on the quality and quantity of fresh groundwater in a low, atoll, Tarawa, in the Republic of Kiribati. We also examine the impacts of groundwater harvesting on traditional subsistence crops such as coconuts and of landuse on water quality. Strategies for reducing risks from climate variations and human impacts and increasing resilience are discussed

Challenges in freshwater management in low coral atolls

Population centres in low atoll islands have water supply problems that are amongst the most critical in the world. Fresh groundwater, the major source of water in many atolls, is extremely vulnerable to natural processes and human activities. Storm surges and over-extractions cause seawater intrusion, while human settlements and agriculture can pollute shallow groundwaters. Limited land areas restrict freshwater quantities, particularly in frequent ENSO-related droughts. Demand for freshwater is increasing and availability is extremely limited. At the core of many groundwater management problems are the traditional water ownership rights inherent in land tenure and the conflict between the requirements of urbanised societies and the traditional values and rights of subsistence communities living on groundwater reserves. Resource limitations and geographic isolation restrict the potential for increasing wealth through crop exports. Water governance reforms and the provision of knowledge to communities are critical. Regional water organisations, fostering self-support, are a key to developing island-adopted and owned solutions

Challenges in freshwater management in low coral atolls

Population centres in low atoll islands have water supply problems that are amongst the most critical in the world. Fresh groundwater, the major source of water in many atolls, is extremely vulnerable to natural processes and human activities. Storm surges and over-extractions cause seawater intrusion, while human settlements and agriculture can pollute shallow groundwaters. Limited land areas restrict freshwater quantities, particularly in frequent ENSO-related droughts. Demand for freshwater is increasing and availability is extremely limited. At the core of many groundwater management problems are the traditional water ownership rights inherent in land tenure and the conflict between the requirements of urbanised societies and the traditional values and rights of subsistence communities living on groundwater reserves. Resource limitations and geographic isolation restrict the potential for increasing wealth through crop exports. Water governance reforms and the provision of knowledge to communities are critical. Regional water organisations, fostering self-support, are a key to developing island-adopted and owned solutions. © 2006 Elsevier Ltd. All rights reserved. (Résumé d'auteur